We’ve all experienced digestive distress from time to time. In fact, up to 70% of athletes go through some sort of gastrointestinal disturbance. It’s particularly common in those who participate in long-duration, high-intensity, dehydrating activities (Coleman 2019). Still, this doesn’t mean we can truly understand what it is like to live with gastrointestinal issues day in and day out. Unfortunately, that’s often the case for people who have irritable bowel syndrome, a condition that affects the large intestine and is characterized by diarrhea, constipation, gassiness, bloating and stomach pain. In some cases, IBS symptoms can be severe, greatly limiting quality of life.

Considering that IBS affects about 10%–15% of the population worldwide (IFFGD 2016), you may have clients who are dealing with these symptoms. What we can do, as fitness professionals, is educate ourselves about the condition so we can better understand how diet can play a role in managing their symptoms.

How Does Diet Relate to IBS?

The cause of IBS is generally still unknown, and unfortunately there is no cure, but there are dietary and lifestyle changes that can improve symptoms. Natalie Digate Muth, MD, MPH, RDN, CSSD, FAAP, says that “in most cases of IBS, it is thought that diet triggers the symptoms. It makes sense, then, that dietary changes may also be an important part of the treatment.”

Specifically, by reducing the amount of fermenting carbohydrates in the diet (and therefore in the gut), some clients may experience a reduction in symptoms. A diet low in these carbohydrates is called a low-FODMAP diet, with FODMAP standing for Fermentable Oligosaccharides, Disac­charides, Monosaccharides and Polyols.

What Are FODMAPs, and Why Can They Be a Problem?

FODMAPs are short-chained carbohydrates found in a wide array of foods, including some fruits and vegetables, as well as wheat, dairy products with lactose, and some natural and artificial sweeteners. (See “FODMAP Foods to Avoid,” below, for some specifics.) As you can see, foods containing FODMAPs are not inherently bad or unhealthy, and many are actually nutrient-dense.

FODMAPs can become a problem because of how they are digested (or not). These foods are osmotic—meaning they draw water into the intestine—and may not be well-absorbed. As a result, they can remain in the gut, where they rapidly absorb water and begin to ferment, producing gas. The results can be abdominal pain, bloating and/or diarrhea.

It is important to note that FODMAP sensitivity is not a food allergy; it is a food intolerance. Fortunately, few people are sensitive to all FODMAP foods. Some individuals may have more sensitivity to particular FODMAP foods, and those who are sensitive to some FODMAP foods in one category are not necessarily sensitive to all foods in that category. Thus, eliminating FODMAP foods entirely and indiscriminately might unnecessarily limit a person’s intake of nutritious food options.

FODMAP: What’s in a Name?

Ice cream on low-FODMAP diet

Disaccharides is lactose, which occurs naturally in some dairy products, including ice cream.

Here’s a quick breakdown of each part of the FODMAP acronym—minus the “A,” which stands for “and.” Sources: Webster 2018; IFFGD 2017.

Fermentation is the anaerobic breakdown of a food—in this case a short-chain carbo­hydrate—that occurs with the help of microbes. In this process, sugars are converted to other compounds, such as alcohol or lactic acid.

Oligosaccharides. There are two different groups of oligosaccharides: fructans and galactans. Fructans are found in wheat, rye and inulin (a fiber additive in many foods) and onions, garlic and artichokes. Galactans are found in beans, chickpeas, lentils and soy-based products, as well as in broccoli and Brussels sprouts. The body cannot absorb oligosaccharides, so they can be a problem for anyone with IBS.

Disaccharides. The most commonly known disaccharide is lactose, which occurs naturally in some dairy products. Milk, yogurt, soft cheeses and ice cream contain lactose—unless, of course, they are labeled lactose-free.

Monosaccharides. Fructose is a monosaccharide found in fruits and some vegetables. Some examples of higher-fructose foods that may cause gastrointestinal symptoms include apples, pears, peaches, cherries, mangoes, watermelon and sugar snap peas. Agave, honey and high-fructose corn syrup also contain fructose.

Polyols are sugar alcohols found in blackberries, cherries, watermelon and some stone fruits, such as apricots, cherries, nectarines, peaches, pears and plums. They are also in some vegetables, like mushrooms and cauliflower. Sugar alcohols (like sorbitol, mannitol, xylitol, maltitol and isomalt) are often used in sugar-free foods like candy and gum, as well as in some cough medicines and cough drops.

FODMAP Foods to Avoid: An Anti-Shopping List

These are some of the most common FODMAP foods. If you have clients with IBS, they may be instructed by their healthcare team to keep these off their grocery list when starting a low-FODMAP diet.

Grains
rye
wheat

Dairy Foods
ice cream
milk
soft cheeses
yogurt
other dairy that is not labeled “lactose-free”

Fruits
apples
apricots
blackberries
cherries
mangoes
nectarines
peaches
pears
plums
watermelon

Vegetables
artichokes
broccoli
Brussels sprouts
cauliflower
garlic
mushrooms
onions

Legumes
beans
chickpeas
lentils
soy-based foods
sugar snap peas

Sweeteners and Food Ingredients
agave
high-fructose corn syrup
honey
inulin (a fiber additive)
maltitol
mannitol
sorbitol
xylitol

How Does a Low-FODMAP Diet Work?

According to a 2018 study by Whelan et al. on the implementation of a low-FODMAP diet, the eating plan consists of a three-step process: “FODMAP restriction; FODMAP reintroduction; and FODMAP personalization.” The study authors say, “It is important that people with IBS do not follow a lifelong restriction.”

Step 1: FODMAP Restriction

The Whelan et al. study recommends an initial restriction phase of 4 weeks, during which intake of any high-FODMAP foods is minimized.

Step 2: FODMAP Reintroduction

This phase is a staged process of introducing one food at a time from each of the FODMAP categories (see “FODMAP Foods to Avoid,” above). “However, there is limited research on the optimal number and order of foods to reintroduce” (Whelan et al. 2018). The purpose of reintroduction is to determine which foods cause symptoms and in what amounts. If a person does not experience symptoms following a food introduction, then there’s no need to keep restricting it. Additionally, if a reintroduced food does cause a reaction, the person may still be able to tolerate it in smaller quantities.

Step 3: Personalization

The end goal of a low-FODMAP diet is a modified-FODMAP diet, meaning that people are able to consume the FODMAP foods they tolerate and to restrict only those that cause symptoms. A separate 2018 study found that “57% of patients experienced adequate symptom relief following such a ‘modified FODMAP diet’ after 6–18 months, including a sustained benefit in 70% of patients who reported adequate relief during initial FODMAP restriction” (O’Keeffe et al. 2018). (Notably, the study lacked a control group and reported data only for those who completed all follow-up.)

A Food-Symptom Journal

Clients diagnosed with IBS can benefit from using a food journal. In addition to having them track dietary intake, as your other clients might do, you can provide the following template for tracking IBS symptoms. Doing this for several days can increase awareness of which foods seem to cause problems and in which quantities. Remind clients to share the results with their registered dietitian and healthcare team, as well as with you.

What Else Does the Research Say About a Low-FODMAP Diet?

Research on low-FODMAP diets is still emerging, and no long-term studies are currently available, but there is evidence to support the implementation of a low-FODMAP eating plan for people experiencing IBS, and there is no benefit to implementing a low-FODMAP diet for people who do not have IBS or are not experiencing similar symptoms. In fact, doing so would unnecessarily restrict foods and thus their nutrients in the diet.

Some examples of recent research:

  • A 2018 meta-analysis of studies on low-FODMAP eating found “evidence of the short-term efficacy and safety of LFD [a low FODMAP diet] in patients with IBS” (Schumann et al. 2018). The analysis looked at nine randomized controlled trials with a total of 596 subjects.
  • A 2017 meta-analysis comparing a low-FODMAP diet with a high-FODMAP diet for patients with IBS found that the former improved IBS symptoms, especially bloating and abdominal pain. Interestingly, this study also mentioned that there is no data confirming that low-FODMAP eating is beneficial in the long run (Altobelli et al. 2017). This supports the use of a low-FODMAP diet in determining which foods a person may be sensitive to and adjusting the diet accordingly.

Final Thought: Remember Your Scope of Practice

Considering that the purpose of a low-FODMAP eating plan is essentially to treat a medical condition, health and fitness coaches must be sure they stay within their scope of practice when discussing this subject with clients. Clients who report symptoms of IBS should be referred to their primary care doctor, who may send them to a gastroenterologist for GI testing. There are multiple health conditions that mimic IBS, and doctors will rule these out before moving forward with a low-FODMAP eating plan.

Also, due to the nature of food restriction and reintroduction in a low-FODMAP diet—and the large number of FODMAP foods—a client interested in trying this approach should be referred to a registered dietitian. This nutrition professional will work to ensure that the client is meeting his or her nutritional needs throughout the process, including those related to fitness and body composition.

By referring out, you are not only adhering to legal and ethical business practices; you are also ensuring that you can focus on your fitness and health coaching, which is what your clients came to you for in the first place.